Add Image Crop/Selection Handle to Existing Java Project

I have a existing Java Uploading program built using Jbuilder which I would like to add the ability to crop the images. The applet works fine but I would like to add this feature when the user selects an image and the preview is put in the panel, I would like for selection handles to be drawn around the image where the user could set a crop area by dragging selection handles to the desired positions, then calculate the area and crop. I can handle the rest from there. Here is a screen grab of the applet and I will probably enlarge the thumbnail display areas a bit to help in the selection. I'm not sure how I'm going to handle giving our my source code.